Effects of nitric oxide and nitrogen on seedling emergence,ion accumulation,and seedling growth under salinity in the euhalophyte Suaeda salsa

Recently nitric oxide (NO) has emerged as a key signal molecule in plants. However, little is known about the role of NO in the salt tolerance of halophytes. Effects of the NO donors sodium nitroprusside (SNP) and nitrate (NO ) on growth and ion accumulation in the euhalophyte Suaeda salsa under salinity were investigated in the present study. The results showed that higher SNP supply increased seedling emergence, but SNP had no effect on shoot growth and the concentrations of Na⁺, K⁺, Cl^–, and NO . Higher NO had no effect on seedling emergence of the species. Shoot Cl^– decreased, but NO₃^– increased markedly, with a higher NO supply. The decrease in the estimated contribution of Cl^– to the osmotic potential was compensated for by an increase in that of NO . It appears that NO plays an important osmotic role in S. salsa under high salinity with a higher NO supply, and this trait may increase salt tolerance of the species under high salinity.     

The influence of salinity on the vegetative growth,osmolytes and chloride concentration of four halophytic species

The aim of this work was to study the influence of salinity of the fertigation solution on the vegetative growth, as well as on the osmolytes and chloride concentration of four halophytic species. Results show that the increase of salinity caused the reduction of plant fresh and dry matter in Asteriscus maritimus, while plant dry weight was unaffected by the salinity in Crithmum maritimum, Halimione. portulacoides and Limonium cossonianum. Salinity enhanced root growth of H. portulacoides. Salt-induced succulence was detected in A. maritimus. The translocation of Cl^– to the leaves is an important factor responsible for salt tolerance of A. maritimus and H. portulacoides. However, C. maritimum and L. cossonianum restricted the uptake of Cl^– and excrete salts through the leaves. Crithmum maritimum and H. portulacoides accumulated proline and soluble sugars in leaves which acts as osmoprotectant. Among the species studied, H. portulacoides has the greatest Cl^– phytoextraction efficiency.     

Water stress effects on biochemical traits and antioxidant activities of wheat (Triticum aestivum L.) under In vitro conditions

Water stress is one of the major environmental stresses that affect agricultural production worldwide, especially in arid and semi-arid regions. This research investigated the effect of water deficit, induced by PEG-6000 on wheat genotypes (GA-2002, Chakwal-97, Uqab-2000, Chakwal-50 and Wafaq-2001) grown in modified MS medium solution. Osmotic stress caused a more pronounced inhibition in leaf relative water content and leaf membrane stability more sensitive (index in Wafaq-2001 and Uqab-2000) genotypes compared with the tolerant (Chakwal-50, GA-2002 and Chakwal-97) genotypes. Upon dehydration, an incline in proline, total soluble sugar, total soluble protein, superoxide dismutase, peroxidase, catalase and malondialdehyde activity content were evident in all genotypes, especially at osmotic stress of ?8 bars. The observed data showed that status of biochemical attributes and antioxidant enzymes could provide a meaningful tool for depicting drought tolerance of wheat genotypes. The present study shows that genotypic differences in drought tolerance could be likely attributed to the ability of wheat plants to induce antioxidant defense under drought conditions. In order to develop genotypes with stable, higher yields in dry farming conditions, it is necessary to characterise genetic resources based on drought adaptation, determine suitable genotypes, and then use them in breeding programmes.     

Effect of salinity on growth and solute accumulation in two wheat lines differing in salt tolerance

Wheat (Triticum aestivum L.) line, Saline Agriculture Research Center line 1 (SARC), was selected in a salinity tolerance improvement program at the University of Agriculture, Faisalabad, Pakistan. In this study we compared SARC with Pothowar which is a common wheat cultivar grown in the same region, in order to study the mechanism of salinity tolerance in the SARC line. Two wheat lines were planted in pots and were subjected to salt stress by daily application of a 200 mM NaCI solution for 30 d during the vegetative growth stage. Dry weight of plant parts, leaf area, leaf water status, and solute concentrations in the cell sap of the leaf tissues were determined at 13 and 30 d after initiation of the stress treatment. Decrease in the plant dry weight and leaf area due to salt stress was more pronounced in Pothowar than in SARC, indicating that SARC was more tolerant to salinity. SARC maintained a higher turgor at low leaf water potentials and showed a higher capacity of osmotic adjustment compared to Pothowar. Major osmotic a that increased by salinity in order to maintain a lower osmotic potential in the two lines were Na⁺, Cl^-, K⁺, and glycinebetaine. Increase in the concentrations of Na⁺, Cl^-, and glycinebetaine was much higher in SARC than in Pothower. These results suggested that the SARC line had a physiological mechanism that conferred a higher salinity tolerance.     

Effect of salt stress on Growth and Ion accumulation of alfalfa (Medicago sativa L.) cultivars

Alfalfa (Medicago sativa L.) yield and nutrient contents may be affected under salinity condition. Thus, this experiment was conducted to determine the effect of three salinity levels (60, 120, and 180 mM NaCl) on shoot and root dry weights, and mineral contents of three alfalfa cultivars. With the increasing salinity levels sodium (Na) and magnesium (Mg) contents increased; but potassium (K), nitrogen (N), phosphorous (P), calcium (Ca), zinc (Zn), and copper (Cu) contents and root and leaf weights decreased; however, changes in these traits depended on cultivar and salinity level. However, Rehnani, a tolerant cultivar, had the lowest Na and Mg contents and the highest K, N, P, Ca, Zn, and Cu contents and dry weights under all of the salinity levels. Moreover, leaf dry weight and leaf P content had the highest correlation with salt tolerance suggesting that these traits may be used as a marker for selecting salts that are tolerant among genotypes in alfalfa.     

Effect of salinity on nitrogen metabolism in wheat

Objectives of our studies were to quantify effects of salinity on growth and nitrogen metabolism of wheat and to measure variation in response of different cultivars, hybrids, and classes. Methods and criteria for identifying resistance to salinity in wheat, particularly effects on nitrogen metabolism also were tested. Variation in response to salinity was measured by subjecting seedlings of six wheats to one control treatment (‐0.1 bars) and two stress treatments (‐3.5 and ‐10.4 bars) from NaCl, MgSO₄, and MgCl₂ in hydroponic solutions. Both stress treatments retarded growth; wheats significantly varied at ‐3.5 bars but not at ‐10.4 bars. Stress decreased root and shoot nitrate N and total N contents. Studies with one wheat cultivar showed that salinity decreased activity of nitrate reductase enzyme and stimulated accumulation of proline. Salinity more adversely affected vegetative stages than reproductive stages of plants grown to maturity. We concluded that salinity affected wheat by both osmotic effects and antagonism of nitrate metabolism from chloride. Absolute growth and relative growth at different stress levels were superior to differences in nitrogen metabolism as selection criteria for salinity tolerance.     

Effect of nitrogen rates applying controlled-release and conventional urea blend in maize

Abstract

Blending polymer-sulfur coated urea (PSCU) and conventional urea (U) for maize (Zea mays L.) fertilization can supply nitrogen (N) during the crop cycle with a single application. Proper placement of PSCU?+?U (0.15?m below and 0.1?m to the side of seed row) in band application at sowing is necessary to reduce salt stress that can decrease dry weight (DU) and N uptake (NU) of maize plant compromising maize yield. It is not clear the proper N rate in the proper placement for band application of PSCU?+?U at maize sowing to avoid salt stress. In the current literature, reduction of N rates are being recommended using PSCU?+?U without consider the probably salt stress provided by high rates of PSCU?+?U. DW and NU in maize plant as well as soil pH and electrical conductivity (EC) were evaluated in a greenhouse pot trial. N treatments were equivalent to 0, 90, 180, 360 and 540?kg N ha^?1 applied incorporated in band in two contrasting soils (Rhodic Eutrustox and Typic Haplustox) using 70%PSCU + 30%U. At V10 (vegetative leaf stage 10), DW and NU of maize aerial part had quadratic behavior in response to increase N rates in the Typic Haplustox soil. In the Rhodic Eutrustox was not observed known behavior for DW and NU in response to increase N rates. Soil pH and EC was higher in the fertilizer row than sowing row. A N rate above of 180?kg N ha^?1 using 70%PSCU + 30%U incorporated in bands can reduce DW and NU in early maize plant growth associated with salt concentration of N fertilizer in a Typic Haplustox soil, which could compromise maize yield.     

Effect of salinity and silicon on root characteristics,growth, water status,proline content and ion accumulation of purslane (Portulaca oleracea L.)

Abstract

A significant part of potentially mineralizable organic nitrogen (N) in soil comprises microbial cells (Bonde et al. 1988). Since the major part of organic N in cow dung also consists of microbial biomass N (Marsh and Campling 1970), it may be worth comparing the origin and the successive processes of N mineralisation in cow dung with those in soil. We studied the effect of the dung beetle, Onthophagus lenzii H., on the decomposition of cow dung and found that the dung beetle played a significant role in this process (Yokoyama et al. 1990). We employed, here, the acid hydrolysis method to analyze the effect of the dung beetle on N transformation in dung balls and residual cow dung.     

The Effect of Arbuscular Mycorrhizal Fungi Inoculation in Mitigating Salt Stress of Pea (Pisum Sativum L.)

ABSTRACT

Salinity is one of the major threats to an agriculture production system and limits crop growth and productivity. Arbuscular mycorrhizal fungi (AMF) form a mutualistic association with majority of land plants and play important role in stress tolerance. In the present study, effect of three mycorrhizal treatments, i.e., single-species AMF (Rhizoglomus intraradices), formulated AMF (Funneliformis mosseae and R. intraradices), and multispecies AMF (Rhizoglomus fasciculatum and Gigaspora sp.) along with control (nonmycorrhizal) on growth, yield performance, and metabolic changes in pea crop under salinity stress was examined in completely randomized design with four replications. The results revealed that AMF inoculation mitigated negative effects of salinity in pea due to higher nutrient uptake, accumulation of compatible osmolytes, and lower cellular leakage of electrolyte which in turn enhanced biomass production, chlorophyll synthesis, yield, and growth attributes. Overall, consortium-based application of R. fasciculatum and Gigaspora sp. was found most suitable approach to ameliorate the salt stress in pea crop and enhanced the yield by ~11%, 24%, and 54% than single-species, multispecies, and control treatments, respectively. The variation in results under different mycorrhizal treatment might be due to specific compatibility relationships that exist between symbionts.     

Silicon and Potassium Nutrition Enhances Salt Adaptation Capability of Sunflower by Improving Plant Water Status and Membrane Stability

The relationships between salinity and mineral nutrition are extremely complex and may change depending on many factors in soil-plant system. We investigated the contribution of silicon (Si at 50 mg kg^?1 soil) and potassium (K at 40 and 60 mg K₂O kg^?1 soil) to improve salt tolerance in sunflower grown with 100 mM sodium chloride (NaCl). The experimental design was factorial based on a completely randomized design with five replications. Added NaCl increased sodium ion (Na⁺) accumulation by 966 percent in shoots and 1200 percent in roots but reduced shoot potassium ion (K⁺) concentration by 49 percent, root K⁺ 51 percent, and shoot K⁺/Na⁺ ratio 95 percent. However, Si and K application effectively reduced Na⁺ accumulation and increased K⁺ concentration and K⁺:Na⁺ ratio, with a significant improvement in plant growth and yield. Among all treatments, greater alleviative effects of Si and K were observed for 50 mg Si + 60 mg K₂O kg^?1 soil, which decreased shoot Na⁺ concentration by 67 percent, root Na⁺ 18 percent, and shoot Na⁺/root Na⁺ ratio 60 percent and increased shoot K⁺ by 198 percent, shoot K⁺/Na⁺ ratio 812 percent, membrane stability index (MSI) 35 percent, relative water content (RWC) 26 percent, and seed weight head^?1 86 percent compared to salt-stressed plants without supplemental Si and K. Most of the plant growth parameters were negatively correlated with Na⁺ accumulation but positively correlated with K⁺ and K⁺/Na⁺ ratio. This study suggests that Si and K mediated reduction in Na⁺ accumulation, and increase in K⁺ concentration, K⁺/Na⁺ ratio, RWC, and MSI are the main factors contributing to improved adaptation capability of sunflower to NaCl stress.     

钾素营养对莲藕生长和干物质累积的影响

采用大盆试验研究了钾素营养对莲藕生长和干物质累积的影响,结果表明,钾素营养明显增加莲藕立叶数量和立叶面积、提高立叶相对叶绿素值和组织器官含水量、延缓叶片衰老、增强立叶抗逆性,从而促进莲藕生育前期光合产物的累积和健康生长;钾素营养还适当延长莲藕成熟期,促进干物质从叶片转移并贮存到产品中,使莲藕增产20.4%.     

Effect of salt stress on growth and biochemical parameters of Pisum sativum L.

Abstract

The effect of salinity on some physio-biochemical parameters in plants of pea (Pisum sativum L. cv. EC 33866) has been investigated. Plants were subjected to four salt treatments, 50, 100, 150 and 200 mM NaCl, for 30 days in sand culture and the physiological responses were measured. Salinity affected all of the considered parameters. Thus, high NaCl concentrations caused a great reduction in growth parameters such as fresh and dry weight of leaves and roots, but the leaf number was less affected. These changes were associated with a decrease in the relative water content and the K⁺ concentrations. The proline and sugar content was increased, but nitrate reductase activity and chlorophyll was found to decrease in leaves. The significance of organic solute accumulation in relation to osmotic adjustment has been discussed.     

氮磷钾对黄芩生长与有效成分累积的影响

探讨氮磷钾营养对黄芩生长动态、产量和有效成分累积的影响,为黄芩的合理施肥提供依据。通过大田试验,采用氮磷钾三因素二次饱和-D最优设计方案(310),定期采样,测定植株的生长指标、根中黄酮和黄芩苷的含量,计算产量,得到合理施肥量。结果表明:单施氮肥最有利于黄芩株高的生长;施磷肥可以促进黄芩根直径、根干重和产量的增加;磷钾配施可以显著提高根冠比和经济系数;单施磷肥最有利于黄芩根中黄酮和黄芩苷的累积。综合考虑各因素,氮磷钾配施优于单施和两两配施,N1P3K3(N 53.13 kg/hm2、P2O5224.89kg/hm2、K2O 224.89 kg/hm2)和N3P3K1(N 149.93 kg/hm2、P2O5224.89 kg/hm2、K2O 79.70 kg/hm2)为较优的两个施肥处理。     

Growth response and nitrogen metabolism of sunflower (Helianthus annuus L.) to vermicompost and biogas slurry under salinity stress

Sunflower was grown under saline media with or without vermicompost amendment and biogas slurry, the organic fertilizers. A randomized complete block design with five replications was used. Forty-five pots were divided in three sets comprising of 15 pots each. Out of 15 pots of each sets, five pots of each were subjected to different levels of saline water irrigation i.e. electrical conductivity (EC): 0.5, 4.8 8.6 dS/m). Amendments of vermicompost and biogas slurry have shown some reduction of sodium induced inhibitory effects. Analyses of fresh and dry weight of leaves, ions, amino acid, protein and nitrogen metabolism enzymes in leaves etc., have been undertaken with reference to above-mentioned treatments. Organic manure amendments improved growth yield, nitrate and protein content and decreased the amount of sodium (Na⁺), chloride (Cl^?), ammonium and total amino acid under saline or non-saline condition. Activities of nitrogen (N)-assimilating enzymes i.e. nitrate reducatse (NR, EC 1.6.6.1), nitrite reductase (NiR, EC 1.6.6.4), glutamine synthetase (GS, EC 6.3.1.2) and glutamate synthase (NADH-GOGAT, EC 1.4.1.14) were enhanced to some extent irrespective to non saline or saline condition. Under salinity NADH-glutamate dehydrogenase (GDH, EC 1.4.1.2) activity was stimulated concomitantly with the increasing ammonium contents and proteolysis activity in the leaves and organic manure did not show a significant difference as compared to their respective control. With respect to salt stress, among the two above-mentioned organic manure, vermicompost showed better result in the entire studied parameter as compared to the biogas slurry.     

Effect of salinity on growth,photosynthesis and mineral composition in leguminous plant Alhagi pseudoalhagi (Bieb.)

Leguminous plant Alhagi pseudoalhagi was subjected to 0 (control), 50, 100, and 200 mM NaCI treatments during a 30 d period to examine the mechanism of tolerance to salinity. Plant dry weight, net CO₂ assimilation rate, leaf stomatal conductance, intercellular CO₂ concentration, and solute concentration in leaves, stems, and roots were determined. Total plant weight in the 50 mM treatment was 170% of that of the control after 10 d of treatment. Total plant weight was lower in the 100 and 200 mM treatments than in the control. The leaf CO₂ assimilation rate was approximately 150% of that of the control in the 50 mM treatment, but was not affected significantly by 100 mM of NaCI, while it was reduced to about 60% of that the control in the 200 mM treatment. Similarly stomatal conductance was consistent with the CO₂ assimilation rate regardless of the treatments. Intercellular CO₂ concentration was lower in the NaCI-treated plants than in the control. Changes in CO₂ assimilation rate due to salinity stress could be mainly associated with stomatal conductance and the carboxylation activity. Although the leaf Na⁺ concentration increased to 900 mmol kg^-1 dry weight in the 200 mM treatment compared to 20 mmol kg^-1 in the control, the plants did not die and continued to grow at such a high leaf Na⁺ concentration. Uptake and transportation rates of Na+, Ca²⁺, Mg²⁺, and K⁺, and the accumulation of N were promoted by 50 mM NaCI. Na⁺ uptake rate continued to increase in response to external NaCI concentration. However, the uptake and transportation rates of Ca²⁺, Mg²⁺, and K⁺ behaved differently under 100 and 200 mM salt stress. The results suggest that A. pseudoalhagi is markedly tolerant to salinity due mainly to its photosynthetic activity rather than to other physiological characteristics.     

盐胁迫下氮素形态对油菜和水稻幼苗离子运输和分布的影响

【目的】土壤盐碱化是制约农作物产量的主要因素之一,盐胁迫影响养分运输和分布,造成植物营养失衡,导致作物发育迟缓,植株矮小,严重威胁着我国的粮食生产。在必需营养元素中,氮素是需求量最大的元素,NO-3和NH+4是植物吸收氮素的两种离子形态。植物对盐胁迫的响应受到不同形态氮素的调控,研究不同形态氮素营养下植物的耐盐机制对提高植物耐盐性及产量具有重要的意义。【方法】本文以喜硝植物油菜(Brassica napus L.)和喜铵植物水稻(Oryza sativa L.)为试验材料,采用室内营养液培养方法,研究了NO-3和NH+4对Na Cl胁迫下油菜及水稻苗期生长状况、对Na+运输和积累的影响,以对照与盐胁迫植株生物量之差与Na+积累量之差的比值,评估Na+对植株的伤害程度。【结果】1)在非盐胁迫条件下,硝态氮营养显著促进油菜和水稻根系的生长;盐胁迫条件下,油菜和水稻生物量均显著受到抑制,Na Cl对供应铵态氮营养植株的抑制更为显著。2)盐胁迫条件下,两种供氮形态下,油菜和水稻植株Na+含量均显著增加,硝态氮营养油菜叶柄Na+显著高于铵态氮营养,叶柄Na+含量/叶片Na+含量大于铵营养油菜,硝态氮营养水稻根系Na+含量显著低于铵营养,地上部则相反。3)铵营养油菜和水稻Na+伤害度显著高于硝营养植株。4)盐胁迫条件下,硝态氮营养油菜地上部和水稻根系K+含量均显著高于铵态氮营养。5)盐胁迫条件下,硝营养油菜和水稻木质部Na+浓度,韧皮部Na+和K+浓度及水稻木质部K+浓度均高于铵营养植株。【结论】与铵营养相比,硝营养油菜和水稻具有更好的耐盐性。硝态氮处理油菜叶柄Na+显著高于铵态氮处理,能够截留Na+向叶片运输。同时,供应硝态氮营养更有利于油菜和水稻吸收K+,有助于维持植物体内离子平衡。盐胁迫下,硝营养油菜和水稻木质部Na+浓度,韧皮部Na+和K+浓度及水稻木质部K+浓度均高于铵营养植株,表明硝态氮营养油菜和水稻木质部-韧皮部对离子有较好的调控能力,是其耐盐性高于铵营养的原因之一。     

Effect of salinity on growth,nodulation and nitrogen assimilation in nodules of faba bean (Vicia faba L.)

A commercial cultivar (Alborea) of faba bean (Vicia faba L. var. minor) was inoculated with salt-tolerant Rhizobium leguminosarum biovar. viciae strain GRA19 in solution culture with different salt concentrations (0, 50, 75 and 100 mmoles l⁻¹ NaCl) added immediately at the time of inoculation. The results indicated that Rhizobium leguminosarum strain GRA19 formed an infective and effective symbiosis with faba bean under saline and nonsaline conditions. Salinity significantly decreased shoot and root dry weight, nodule weight and mean nodule weight. Roots were more sensitive than shoots, and N₂ fixation was more sensitive to salinity than was plant growth. Analyses of ammonium assimilating enzymes in the nodule showed that glutamine synthetase appeared to be more tolerant to salinity than glutamate synthase, and that it limits ammonium assimilation under saline stress.     

Comparative growth and physiological responses of two wheat (Triticum aestivum L.) cultivars differing in salt tolerance to salinity and cyclic drought stress

Two cultivars of wheat (Triticum aestivum L.) with differential salinity tolerance were compared by evaluating the growth attributes, pigment composition and accumulation of Na⁺, K⁺, Zn²⁺, Fe ²⁺, Mn ²⁺ and proline. Wheat cultivars Al-Moiaya (AM) (salt tolerant) and Habbe-Druma (HD) (salt sensitive) were subjected to four levels of salinity (1.21 dS m^?1, 4.4 dS m^?1, 8.8 dS m^?1 and 13.2 dS m^?1) in factorial combinations with three drought stress (FC 30%, FC 60% and FC 90%) treatments in a randomized complete block design. Plant dry weight, leaf area ratio (LAR), soluble protein and total chlorophyll (Chl) content were higher in AM than HD. Salt-tolerant AM maintains a higher K⁺/ Na⁺ ratio and thereby is able to grow better than the salt-sensitive HD under both the stresses. The lower foliar Na⁺ in AM resulted in retention of higher Chl content, reflected in the strong positive correlations between plant ion status and Chl contents (Na⁺-Chl r² = 0.83; Chl- Fe²⁺ r² = 0.76; Zn²⁺ r² = 0.93 and Mn²⁺ r² = 0.88). In conclusion, our results suggested that the K⁺/Na⁺ ratio, exclusion of Na⁺ and ion homeostasis play much more important roles in the tolerance to salinity and drought stress than the compatible osmolyte, proline.     

Effect of salinity and soil temperature on the growth and physiology of drip-irrigated rice seedlings

Drip irrigation offers potential for rice (Oryza sativa L.) production in regions where water resources are limited. However, farmers in China’s Xinjiang Province report that drip-irrigated rice seedlings sometimes suffer salt damage. The objective of this study was to learn more about the effects of soil salinity and soil temperature on the growth of drip-irrigated rice seedlings. The study consisted of a two-factor design with two soil salinity treatments (0 and 1.8 g kg^?1 NaCl) and three soil temperature treatments (18°C, 28°C and 36°C). The results showed that shoot biomass, root biomass and root vigor were greatest when seedlings were grown with no salt stress (0 g kg^?1 NaCl) at 28°C. Moderate salt stress (1.8 g kg^?1 NaCl) combined with high temperature (36°C) significantly reduced root and shoot biomass by 39–53%. Moderate salt stress and high temperature also increased root proline concentration by 77%, root malonyldialdehyde concentration by 60% and seedling mortality by 60%. Shoot and root Na⁺ concentrations, shoot and root Na⁺ uptake and the Na⁺ distribution ratio in shoots were all the greatest when moderate salt stress was combined with high temperature. In conclusion, high soil temperature aggravates salt damage to drip-irrigated rice seedlings. Therefore, soil salinity should be considered before adopting drip-irrigation for rice production.     

Effect of nitrogen,phosphorus and potassium fertilizer on growth and seed germination of Capsella bursa-pastoris (L.) Medikus

We investigated how plant height, number of stem and branch, seed production and seed germination of Capsella bursa-pastoris were affected by nitrogen (N), phosphorus (P) and potassium (K) fertilizer using a pot fertilizer experiment. Plant growth parameter was determined, and fully ripen seeds were tested for germination. C. bursa-pastoris exhibited great phenotypic variation in plant height, number of stem and branch in relation to N, P and K supply. Seed production per plant was lowest in the control and low P treatment, and highest in NPK treatment. More than 16,000 seeds per plant were produced in treatments where N and P were applied together. A balanced N, P and K supply results in producing a high percentage and fast germinating seeds, while a deficiency of P and K together with a high N supply results in low germination ability and fast germinating of the produced seeds in C. bursa-pastoris.